GEORGIUS AGRICOLA ON THE ORIGIN AND CAUSES OF SUBTERRANEAN THINGS, Book One.

A woodcut depicts an ornamental initial letter 'V'. Inside the letter, a figure—likely a scholar—sits within a rocky, cavernous landscape, examining a vein of mineral or ore.

Having determined to investigate the natures of those things which are born within the earth, it is not inconsistent with the established method to first contemplate their origins and causes. Yet, since what nature generates in the channels of the earth, and indeed in every inner crevice and bosom of its interior, partly bursts forth from the earth into the air by its own power—such as moisture, air, exhalation, and fire—and is partly dug out—such as notable earth, thickened juice e.g., bitumen or resins, stone, metal, and what is mixed—I shall first pursue the origins, effects, and causes of the qualities of those things that fall under the first category. For they are either elements, or they approach most closely to the nature of elements, and from them, together with the earth, the things categorized under the second genus are formed. Moreover, since moisture embraces two species—namely, water and juice—and since water is thin and almost simple, whereas juice is thick and always mixed, I shall first attempt to find the origin of water.

Therefore, the question is raised: does all the water that flows from springs, or emerges from the sides or bottoms of wells, collect from rain, or does it have an origin? Does the earth conceive one part from rains, while another part is generated within its own channels and caverns? Those who wish for all water to be collected from rain are accustomed to conclude it in this manner. In regions where frequent and great rains fall—such as those temperate in the moderation of heat and cold, and those situated in northern or southern parts—very many springs gush forth, from which many brooks and rivers arise and irrigate the land. Conversely, in regions where rains are almost denied by nature and fall very rarely—such as those scorched by the perpetual heat of the sun during the day—springs gush forth very rarely, and few rivers flow, unless led into them from mountains and far-distant places. Therefore, they say, all spring and well water is collected from the rains which the earth drinks up.

Others, however, as Aristotle mentions, say: water is carried on high by the sun. When it rains in turn, and the earth drinks the rain, it flows together into one place and then flows as if from some great reservoir. Either all rivers flow from one reservoir, or one from another, and no water is generated. But in winter, being gathered into the beginnings of this kind, it pours out a wealth of rivers. For this reason, rivers always abound more with water in winter than in summer, and some are perennial while others are not. For those in which so much water is collected because of the size of the reservoir,